Video coding for wireless varying bit-rate communications based on area of interest and region representation

A coding method for videophone communications over wireless, varying bit-rate, channels, is proposed. This method is based on defining one or more areas of interest and breaking them into a number of arbitrarily shaped regions which are homogeneous in their motion. The interest areas in the current implementation are human faces. They are detected with the help of a 2D scene model which is a-priori constructed and is based on knowledge of the application context. A mixed intra/inter-frame coding method is used for the description of the shape and topology of the regions where each polygonal vertex is encoded in a costless manner, either with regards to its predecessor in the same frame, or to the corresponding vertex in the previous frame. This coding is based on rate/distortion optimization constrained by the instantaneously available bit-rate. The error coding is also performed in an adaptive prioritized manner and is restricted within the detected areas of interest